Grate the potatoes, carrots, and the onion into a large bowl. Drain off the liquid that will accumulate around the edges of the mixture before going on.
Stir in all the remaining ingredients. But add the milk powder carefully to avoid lumps.
Spread the mixture evenly in an oiled pan. Place it in a 350°F oven for 40 minutes to an hour. (The square pan will take longer than the 7" x 11") When the kugel is nearly done it will test dry like a cake, the edges should be brown, and it will smell delicious. Before you remove it from the oven, add the grated cheese, either 1/3 or 1 cup. Leave it for about 5 more minutes, or until the cheese is completely melted.
If you are using the smaller amount of cheese, serve the yogurt at the table using about 2 tablespoons per square. It is just as delicious with the full cup of grated cheese and yogurt. And for serving cold, the yogurt isn't necessary for complete protein.